Executive Summary

EPA has completed its review of public comments on the revised risk
assessments and is issuing its risk management decisions for temephos.
The risk management and regulatory decisions outlined in this document
represent the final reregistration eligibility decision for temephos.
Because there are no tolerances and no likely exposure from drinking
water or residential use, temephos will not be included in the cumulative
assessment for organophosphate pesticides.

The revised risk assessments are based on review of the required target
data base supporting the use patterns of currently registered products
and new information received. The Agency invited stakeholders to provide
proposals, ideas or suggestions on appropriate mitigation measures before
the Agency issued its risk mitigation and eligibility decisions on temephos.
After considering the revised risks, as well as mitigation proposed
by Clarke Mosquito Control Company, Inc., the registrant of temephos'
technical product, and comments and mitigation suggestions from other
interested parties, EPA developed its risk management decision for uses
of temephos that pose risks of concern. These decisions are discussed
fully in this document.

Temephos is an organophosphate insecticide currently used primarily
as a mosquito larvicide.

EPA considers this to be a public health use. As such, the Agency has
considered the provisions of FIFRA, as amended by FQPA, related to public
health pesticides in its regulatory decision, including consultation
with the Department of Health and Human Services (HHS) concerning the
public health risk of mosquito-transmitted diseases and the benefits
of temephos use. Information received from HHS confirms EPA's evaluation
of temephos as the only organophosphate with any appreciable mosquito
larvicidal use. It is effective against a wide spectrum of mosquitos,
including those that transmit Eastern equine encephalitis, St. Louis
encephalitis, dengue fever, and West Nile virus. It is more effective
than available alternatives in highly polluted water, and tidal zones.
As such, it is considered to be an important management tool in mosquito
abatement programs.

Use of temephos has declined in recent years, with current annual
usage of about 25,000 to 40,000 lbs of active ingredient. All remaining
food tolerances were revoked in 1998.

Overall Risk Summary

EPA's human health risk assessment indicates some risks of concern
for some pesticide handlers and applicators who mix, load, and apply
temephos for mosquito abatement. Because there are limited re-entry
activities associated with mosquito larvicide applications, post-application
risk to workers is not a concern. There are no food uses and exposure
from drinking water is expected to be negligible due to its use only
in non-potable water (stagnant, saline, brackish and temporary water
bodies). There are no residential or homeowner uses of temephos, and
again, because of its limited use pattern no significant exposure is
expected to children or the general population.

Temephos is not expected to have a direct impact on terrestrial animals.
Risk quotients for freshwater fish only slightly exceed levels of concern;
no acute toxicity data are available for marine fish species. Field
monitoring data indicate little impact on birds. Aquatic invertebrates,
particularly Daphnia magna, are extremely sensitive to temephos.
Monitoring data show that populations reestablish rapidly, but diversity
may be affected.

Risk Mitigation

To address risk concerns posed by the use of temephos, EPA considered
the mitigation proposal submitted by the technical registrant, as well
as comments and mitigation ideas from other interested parties. The
Agency has concluded that a number of label amendments are necessary.
Results of the risk assessments, and the label amendments necessary
to mitigate those risks, are presented in this RED.

To address occupational risk concerns, additional personal protective
equipment (PPE) will be needed. Closed systems for mixing and loading
would also address occupational risks for these activities and this
option will be provided on new labels. In addition, the registrant has
agreed to remove from product labels the use of certain hand held equipment
(belly grinder) with the highest risk. No data are available to assess
the risk from the use of power backpack blowers to apply temephos granules
to tire piles. This is a minor but critical use--the granular temephos
product is uniquely formulated for penetration of large tire piles and
provides residual effectiveness. EPA is requiring data to assess exposure
from this use and additional PPE will be needed. A 21-day dermal toxicity
study is necessary as confirmatory data. The results of this study,
if submitted in a timely fashion, may allow for reconsideration of some
or all of the necessary PPE and engineering controls.

To address ecological risks, certain label restrictions are needed.
Temephos labels will need to specify intervals between applications,
further limit use sites to ensure that drinking water sources are not
treated, and limit the circumstances under which the highest application
rates may be used. In addition, the registrant has agreed to include
reference to EPA's endangered species web site on product labels.

Reregistration Eligibility

For the mosquito, midge, gnat, punkie, and sandfly larvicidal use of
temephos the Agency has determined that, with the adoption of all of
the label amendments noted in this document, these uses are eligible
for reregistration.

The Agency is issuing this Reregistration Eligibility Decision (RED)
for temephos, as announced in a Notice of Availability published in
the Federal Register. This RED document includes guidance and
time frames for complying with any necessary label changes for products
containing temephos. There is no additional comment period for this
RED and the time frames for compliance with the necessary changes outlined
in this document are shorter than those given in previous REDs. As part
of the process discussed by the TRAC, which sought to open up the process
to interested parties, the Agency's risk assessments for temephos have
already been subject to numerous public comment periods, and a further
comment period for temephos was deemed unnecessary. The Phase 6 of the
pilot process did not include a public comment period; however, for
some chemicals, the Agency may provide for another comment period, depending
on the content of the risk management decision. With regard to complying
with the requirements in this document, the Agency has shortened this
time period so that the risks identified herein are mitigated as quickly
as possible. Because there are no food or residential uses, and drinking
water is unlikely to be contaminated with temephos, no further cumulative
assessment will be needed.

I. Introduction

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was
amended in 1988 to accelerate the reregistration of products with active
ingredients registered prior to November 1, 1984. The amended Act calls
for the development and submission of data to support the reregistration
of an active ingredient, as well as a review of all submitted data by
the U.S. Environmental Protection Agency (referred to as EPA or "the
Agency"). Reregistration involves a thorough review of the scientific
database underlying a pesticide's registration. The purpose of the Agency's
review is to reassess the potential hazards arising from the currently
registered uses of the pesticide; to determine the need for additional
data on health and environmental effects; and to determine whether the
pesticide meets the "no unreasonable adverse effects" criteria
of FIFRA.

On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was
signed into law. This Act amends FIFRA to require tolerance reassessment
of all existing tolerances. The Agency had decided that, for those chemicals
that have tolerances and are undergoing reregistration, the tolerance
reassessment will be initiated through this reregistration process.
It also requires that by 2006, EPA must review all tolerances in effect
on the day before the date of the enactment of the FQPA, which was August
3, 1996. FQPA also amends the FFDCA to require a safety finding in tolerance
reassessment based on factors including an assessment of cumulative
effects of chemicals with a common mechanism of toxicity. Temephos belongs
to a group of pesticides called organophosphates, which share a common
mechanism of toxicity - they all affect the nervous system by inhibiting
cholinesterase. Although FQPA significantly affects the Agency's reregistration
process, it does not amend any of the existing reregistration deadlines.
Therefore, the Agency is continuing its reregistration program while
it resolves the remaining issues associated with the implementation
of FQPA.

This document presents a brief summary of the Agency's revised human
health and ecological risk assessments, and final reregistration eligibility
decision for temephos. Based on the current limited use pattern, no
cumulative assessment will be necessary for temephos.

The implementation of FQPA has required the Agency to revisit some
of its existing policies relating to the determination and regulation
of dietary risk, and has also raised a number of new issues for which
policies need to be created. These issues were refined and developed
through collaboration between the Agency and the Tolerance Reassessment
Advisory Committee (TRAC), which was composed of representatives from
industry, environmental groups, and other interested parties. The TRAC
identified the following science policy issues it believed were key
to the implementation of FQPA and tolerance reassessment:

Applying the FQPA 10-Fold Safety Factor

Whether and How to Use "Monte Carlo" Analyses in Dietary
Exposure Assessments

How to Interpret "No Detectable Residues" in Dietary
Exposure Assessments

Refining Dietary (Food) Exposure Estimates

Refining Dietary (Drinking Water) Exposure Estimates

Assessing Residential Exposure

Aggregating Exposure from all Non-Occupational Sources

How to Conduct a Cumulative Risk Assessment for Organophosphate
or Other Pesticides with a Common Mechanism of Toxicity

Selection of Appropriate Toxicity Endpoints for Risk Assessments
of Organophosphates

Whether and How to Use Data Derived from Human Studies

The process developed by the TRAC calls for EPA to provide one or more
documents for public comment on each of the policy issues described
above. Each of these issues is evolving and in a different stage of
refinement. Some issue papers have already been published for comment
in the Federal Register and others will be published shortly.

In addition to the policy issues that resulted from the TRAC process,
the Agency issued on Sept. 29, 2000, a Pesticide Registration Notice
(PR 2000-9) that presents EPA's approach for managing risks from organophosphate
pesticides to occupational users. The Worker PR Notice describes the
Agency's baseline approach to managing risks to handlers and workers
who may be exposed to organophosphate pesticides, and the Agency expects
that other types of chemicals will be handled similarly. Generally,
basic protective measures such as closed mixing and loading systems,
enclosed cab equipment, or protective clothing, as well as increased
reentry intervals will be necessary for most uses where current risk
assessments indicate a risk and such protective measures are feasible.
The policy also states that the Agency will assess each pesticide individually,
and based upon the risk assessment, determine the need for specific
measures tailored to the potential risks of the chemical. The measures
included in this RED are consistent with the Worker Pesticide Registration
Notice.

This document consists of six sections. Section I. contains the regulatory
framework for reregistration/tolerance reassessment as well as descriptions
of the process developed by TRAC for public comment on science policy
issues for the organophosphate pesticides and the worker risk management
PR notice. Section II. provides a profile of the use and usage of the
chemical. Section III. gives an overview of the revised human health
and environmental effects risk assessments resulting from public comments
and other information. Section IV. presents the Agency's reregistration
eligibility and risk management decisions. Section V. summarizes necessary
label changes based on the risk mitigation measures outlined in Section
IV. Section VI. provides information on how to access related documents.
Finally, the Appendices lists Data Call-In (DCI) information. The revised
risk assessments and related addenda are not included in this document,
but are available on the Agency's web page http://www.epa.gov/pesticides/reregistration/status.htm,
and in the public docket.

II. Chemical Overview

A. Regulatory History

Temephos was first registered in the United States in 1965 by American
Cyanamid Company for a number of uses including citrus fruits, pet collars,
and mosquito control. A Registration Standard was issued in August,
1981. In response to EPA's 1991 Data Call-In, American Cyanamid dropped
all uses except the mosquito larvicide use in non-potable waters and
requested a low volume minor use waiver for relief from the data requirements
associated with that use. EPA found the waiver justified on economic
grounds and waived some of the requirements. In 1997, the temephos technical
registration was transferred to Clarke Mosquito Control Products, Inc.
The Agency has revoked all food tolerances for temephos. See the Federal
Register (63 FR 5910) published on February 5, 1998.

Timing -No intervals are given on current labels. Multiple applications
per season are permitted. Rate and frequency depend on the organic content
of the water being treated, climatic conditions, infestation levels,
and other regional and site-specific factors.

Use Classification: General

D. Estimated Usage of Pesticide

This section presents the best estimates available for the uses of
temephos, based on available pesticide usage information for 1987 through
1998. A full listing of all uses of temephos with the corresponding
use and usage data for each site, has been completed and is in the "Quantitative
Use Assessment" (QUA) document, which is available in the public
docket and on the Agency's website. It should be noted that the QUA
contains usage information for sites that are no longer registered.
The data, reported on an aggregate and site (crop) basis, reflect annual
fluctuations in use patterns as well as the variability in using data
from various information sources. Historically, as much as 100,000 lbs
ai were used annually. For a better understanding of current usage,
EPA has also consulted survey information from the American Mosquito
Control Association (AMCA). Approximately 25,000 to 40,000 lbs ai of
temephos are currently used annually, according to Agency and registrant
estimates. Although temephos is used in many areas of the US, Florida
and New Jersey are the states with most usage.

III. Summary of Temephos Risk Assessment

Following is a summary of EPA's revised human health and ecological
risk findings and conclusions for the organophosphate pesticide temephos,
as fully presented in the documents, "TEMEPHOS: Revised HED Chapter
for the Reregistration Eligibility Decision (RED) Document," dated
September 29, 1999 and the EFED "Reregistration Eligibility Document
for Temephos," dated October 4, 1999. The purpose of this summary
is to assist the reader by identifying the key features and findings
of these risk assessments, and to better understand the conclusions
reached in the assessments.

These risk assessments for temephos were presented at a October 13,
1999, Stakeholders Meeting in Orlando, Florida, which was followed by
an opportunity for public comment on risk management for this pesticide.
The risk assessments presented here form the basis of the Agency's risk
management and eligibility decision for temephos only.

A. Human Health Risk Assessment

EPA issued its preliminary risk assessments for temephos in September,
1998 (Phase 3 of the TRAC process). In response to comments and studies
submitted during Phase 3, the risk assessments were updated and refined.
Major revisions to the preliminary human health risk assessment include
incorporation of a 38% dermal absorption factor based on a literature
study provided by the registrant and correction of the maximum application
rate for the emulsifiable concentrate--the preliminary assessment had
assumed 0.5 lbs/ai/A; the correct rate is 0.0469 lbs/ai/A.

Only an occupational (mixer, loader, and applicator) risk assessment
was conducted for temephos. The Agency believes that it is unlikely
that significant postapplication exposures would occur based on the
low application rate, the short duration spent by the worker in a treated
area, and the low exposure activities performed by the worker.

Because of its limited use pattern, no residential, dietary, or drinking
water exposures are likely and thus no risk assessments were warranted.
Use sites include outdoor non-food and non-domestic aquatic areas such
as non-potable water (stagnant, saline, brackish and temporary water
bodies), waters high in organic content, highly polluted water, including
moist areas, woodland pools, shallow ponds, edges of lakes, swamps,
marshes, tidal waters, intertidal zones, catch basins, and tire piles.
These use sites are typically unusable as sources of drinking water.
Because of the areas in which temephos is aerially applied (e.g., tidal
marshes) and the presumed large droplet size of the spray, the Agency
believes it is unlikely that significant exposure via spray drift would
occur. However, because of the diversity of sites on which temephos
may be used, the Agency is concerned that bystander spray drift exposure
may occur in some situations. Although temephos may be used in areas
that may occasionally be visited by the general population (e.g., temporary
pools along the side of the road, standing water in discarded tires),
the Agency believes that postapplication exposure would be minimal.
This belief is based on the relatively low application rate, the likelihood
of a brief duration spent in such environments, and the probability
of low exposure activities in these areas.

FQPA Safety Factor

The FQPA Safety Factor Committee determined that the 10X for temephos
should be retained solely because of the inadequacy of the toxicology
data base which precluded an evaluation of potential enhanced susceptibility
to infants and children. However, an FQPA safety factor for the protection
of infants and children from exposure to temephos was not used in the
risk assessment because presently there are no registered food, drinking
water, or residential uses, and thus there are no concerns for potential
exposures of infants and children to temephos. For these reasons, only
occupational risk assessments were conducted for temephos, and, as a
matter of policy, the FQPA factor is not considered in occupational
assessments. For additional information see "Report of the Hazard
Identification Assessment Review Committee," dated May 12, 1998,
available in the public docket and on the Internet.

1. Occupational Risk

In general, occupational workers can be exposed to a pesticide through
mixing, loading, and/or applying a pesticide, or re-entering treated
sites. For temephos, occupational handlers include: personnel of mosquito
abatement districts (MADs) and personnel of companies under contract
to MADs, and other state and local public health authorities.

The Agency believes that it is unlikely that significant postapplication
exposures to temephos would occur either to workers or by-standers based
on the relatively low application rate, the limited use pattern, the
short duration spent by the worker or bystanders in the types of areas
treated, and the low exposure activities, such as sampling, performed
by the re-entry worker. Thus, no post-application assessment has been
conducted.

Risk for all of these potentially exposed populations is measured by
a Margin of Exposure (MOE) which determines how close the occupational
exposure comes to a No Observed Adverse Effect Level (NOAEL). Generally,
MOEs greater than 100 are not of concern.

a. Toxicity

The toxicity of a chemical is integral to assessing the occupational
risk. All risk calculations are based on the most current toxicity information
available for temephos. A valid 21-day dermal toxicity study was not
available to assess temephos. The toxicological endpoints, and other
factors used in the occupational risk assessments for temephos are discussed
in more detail below.

The toxicology database for temephos has several data gaps. Most of
the available studies were conducted in the 1960's and 1970's and do
not meet the current requirements of Subdivision F Guidelines. However,
the Agency has reviewed all toxicity studies submitted and has determined
that available data are adequate to support the reregistration of temephos
for non-food, non-residential, low-volume, minor use.

Temephos has relatively low to moderate acute toxicity compared to
other organophosphate insecticides. Temephos is moderately acutely toxic
by the oral and dermal route, and has low toxicity through inhalation.
Signs of toxicity observed in animals treated with high doses of temephos
are typical of acute toxicity signs induced by cholinesterase (ChE)
inhibition which include; hypoactivity, labored breathing, rough coat,
chromodacryorrhea, salivation, muscle spasms and tremors. Temephos is
slightly irritating to eyes but is not a skin irritant or a dermal sensitizer.

Table 1. Summary of Acute Toxicity Data for Temephos

Guideline#

Study Type

MRID

Results

Toxicity
Category

870.1100

Acute Oral (Rats)

000019021

LD50= 444 mg/kg

II

870.1200

Acute Dermal (Rabbits)

140124
1906/1907

LD50 = 1850 mg/kg (Males)
LD50 = 970 mg/kg (Females)

II
II

870.1300

Acute Inhalation

00101656

LC50 > 1.3 mg/L

III

870.2400

Primary Eye Irritation

001907

Corneal opacity 72 hrs

III

870.2500

Primary Skin Irritation

140124

PIS = 1.4

IV

870.2600

Dermal Sensitization

00157836

Not a sensitizer

Note: The information in this table is based on studies used to support
the original registrations of temephos products. These data may not
be acceptable by current guideline standards. New acute toxicity data
will be necessary and reviewed as a result of the PDCI that accompanies
this RED.

A complete assessment of the neurotoxic potential of temephos cannot
be made since acute and subchronic neurotoxicity studies in rats are
not available. Nevertheless, temephos belongs to the class of organophosphorus
insecticides which exert their toxic action by inhibiting cholinesterase
in the peripheral and central nervous systems and therefore, neurotoxicity
is implied in this class of chemicals.

Temephos is not considered to be a reproductive or developmental toxicant.
Additional data are necessary to confirm this assessment. Since there
are no current registered food or residential uses, there are no concerns
for potential exposure to infants and children.

Temephos is not classified as a carcinogen. The only study available
for this assessment was a 2-year chronic study in rats, in which the
highest dose (15 mg/kg/day) did not induce tumor formation. In addition,
several in vitro mutagenicity studies were considered not adequate
to evaluate the genotoxic potential of temephos. Because this chemical
is for non-food use only, a chronic/carcinogenicity study in another
species is not necessary.

A NOAEL of 0.3 mg/kg/day was selected for the short-term, intermediate-term,
and long-term or chronic occupational risk assessments. This endpoint
is based on inhibition of cholinesterase in the red blood cells of rats
of both sexes at 0.9 mg/kg/day (LOAEL) in a 90-day feeding study. The
toxic effect was observed within one week after initiation of treatment,
and thus is considered to be appropriate for a short term (1-7 day)
assessment. Use of this same endpoint for the chronic assessment is
supported by similar doses and endpoints seen in another subchronic
toxicity study in rats, as well as a chronic study in dogs where red
blood cell and plasma cholinesterase inhibition occurred from one week
onward.

No short, intermediate or chronic inhalation study is available. Therefore,
the oral NOAEL of 0.3 mg/kg/day was also used to estimate inhalation
risk and to perform a combined dermal and inhalation assessment.

Further details on the toxicity of temephos can be found in the September
29, 1999 Human Health Risk Assessment. The studies and endpoints used
for the occupational risk assessment are outlined in Table 2.

b. Dermal Absorption

No acceptable guideline dermal absorption studies are available for
temephos. A rabbit dermal study was conducted, however this study was
not considered adequate. Dermal rabbit studies can be expected to underestimate
the toxicity of sulfur-containing organophosphates, such as temephos,
because rabbit blood has high concentrations of arylesterases, a class
of enzymes which detoxify the compounds before they can be converted
to the activated form in the liver. For this reason, the rat is the
preferred species for dermal studies for many organophosphates.

During Phase 3 of the OP process, the registrant submitted a published
dermal absorption study of temephos (MRID 44756801) conducted by the
Department of the Army. EPA has reviewed the study, and determined that
a dermal absorption factor of 38% is appropriate for use in the revised
assessment.

The registrant and other commenters questioned the Agency choice of
38% dermal absorption in the rat, since the Army study had also estimated
lower dermal absorption values for dogs and rabbits. EPA's conclusion
of 38% dermal absorption was calculated using experimentally derived
values from the submitted non-guideline study using the rat. While the
rat was not intended as a model of dermal absorption to predict penetration
through the human skin, the rat has been extensively used for metabolic
and toxicological studies and allows for consistency and comparisons
from study to study and the Agency believes it is reasonable to use
the rat as the preferred species for dermal absorption studies. Furthermore,
in this case, the Agency's does not believe it is appropriate to compare
relative dermal absorption across species because there is considerable
species variation in dermal penetration and subsequent responses to
toxicants due to inherent physiological differences.

Table 2. Summary of Toxicological Endpoints and Other Factors Used
in the Human Occupational Risk Assessments for Temephos

Assessment

Dose

Endpoint

Study

Absorption factor

Short-term dermal

NOAEL = 0.3 mg/kg/day

RBC ChE inhibition at 0.9mg/kg/day at week one

90-day oral Feeding Study in Rats

38%

Intermediate- term dermal

NOAEL = 0.3 mg/kg/day

RBC ChE inhibition at 0.9mg/kg/day

90-day oral Feeding Study in Rats

38%

Long-term dermal

NOAEL= 0.3 mg/kg/day

RBC ChE inhibition at 0.9mg/kg/day

90-day oral Feeding Study in Rats

38%

Inhalation--any time period

NOAEL= 0.3 mg/kg/day

RBC ChE inhibition at 0.9mg/kg/day

90-day oral Feeding Study in Rats

100%

c. Exposure

No chemical-specific exposure data were available for temephos, so
risks to pesticide handlers were assessed using data from the Pesticide
Handlers Exposure Database (PHED). The standard assumption of 70 kg
was used for average body weight. Temephos-specific usage data were
available from the American Mosquito Control Association and individual
MADs to characterize the typical application rates and daily areas treated,
which EPA used to calculate volume of pesticide handled for their risk
estimates. The quality of the data and exposure factors represents the
best sources of data currently available to the Agency for completing
these kinds of assessments. Although available usage data indicate that
maximum application rates are used only infrequently, they have also
been taken into account in the assessment because they are allowed on
current temephos labels, and registrants wish to retain those high rates
for use under certain critical conditions. PHED unit exposure values,
although derived from agricultural use, are currently the best available
estimates of exposure for mosquito control operations. Some PHED unit
exposure values are high quality while others represent low quality,
but are the best available data. The quality of the data used for each
scenario assessed is discussed in the Human Health Assessment document
for temephos, which is available in the public docket and on the Agency's
website.

Anticipated use patterns and application methods, range of application
rates, and daily acres treated were derived from current labeling and
information supplied by stakeholders. The maximum application rate specified
on current temephos labels for granular formulations is 0.5 lbs/ai/A;
typical application rate for granular products ranges from 0.1 to 0.3
lbs/ai/A; the granular tire treatment is applied at a rate of 0.05 lbs/ai/100
sq. ft. Maximum application rate for the emulsifiable concentrate (EC)
is 1.5 fl. oz./A (0.0469 lbs/ai/A); typical application rate for the
EC is 0.5 to 1.0 fl. oz./A (0.0156 to 0.0313 lbs/ai/A).

Occupational handler exposure assessments are conducted by the Agency
using different levels of personal protection. The Agency typically
evaluates all exposures with minimal protection and then adds additional
protective measures using a tiered approach to obtain an appropriate
MOE (i.e., going from minimal to maximum levels of protection). The
lowest tier is represented by the baseline exposure scenario, followed
by, if required (i.e., MOEs are less than 100), increasing levels of
risk mitigation (personal protective equipment and engineering controls).
The current labels for temephos require no protective equipment [not
even baseline works clothes, with the exception of the label for the
granular tire treatment product (EPA registration #8329-30) which requires
handlers to wear safety goggles]. Information from stakeholders indicates
that typical practice is to wear baseline work clothes and usually gloves,
even though these requirements are not yet on product labels. The levels
of protection that formed the basis for calculations of exposure from
temephos activities include:

Baseline: Long-sleeved shirt and long pants, shoes and socks.

Current Label: No PPE is required on current labels except goggles
which are required on the granular formulation used to treat tire piles.
The current label scenario was not assessed but MOEs would be less than
the baseline values given in Table 3.

Engineering controls: Engineering controls such as a closed cab truck
or closed cockpit for application scenarios, or a closed mixing/loading
system such as a mechanical transfer system for emulsifiable concentrate
or a packaged based system (e.g., a lock and load type system for granulars).
Some engineering controls are not applicable for certain scenarios (e.g.,
for hand held application methods there are no known devices that can
be used to routinely lower the exposures). EPA is not aware of any closed
loading systems for granular application by aircraft.

Dermal exposure is the primary route of concern. Risk from inhalation
exposure would be minimal, based on the lack of toxic effects near or
above the limit dose in an acute inhalation toxicity study. Occupational
handlers can be exposed to temephos on a short term, intermediate term,
and long term (chronic) basis. Information from the registrant and user
community indicates that workers could be exposed up to five days per
week for the 6 warm months and 2-3 times per week for the rest of the
year. Typical exposures may be less and vary by region.

The Agency believes that it is unlikely that significant postapplication
exposures to temephos would occur either to workers or by-standers based
on the relatively low application rate, the limited use pattern, the
short duration spent by the worker or bystanders in the types of areas
treated, and the low exposure activities performed by the re-entry worker.
Thus no post-application assessments have been conducted.

d. Occupational Handler Risk Summary

The representative treatment scenarios considered for mixers, loaders,
and applicators are listed below:

(12) No data are available to assess exposure from power backpack
blowers.

The engineering controls for each scenario are listed below:

(1, 2, 3) Closed mixing and loading systems.

(4, 5, 7, 8) Closed cockpit.

(6) Engineering controls were not considered for rights-of-way sprayer
applications. EPA assumes that these types of applications involve an
individual on the back of a tank truck directing the pesticide spray
with a hose.

Data from PHED for helicopter application of sprays and granulars are
based on a very limited number of replicates. Instead of assessing this
exposure scenario using inadequate data, EPA assumes that the estimates
for helicopters are similar to those for fixed-wing applications.

Combined dermal and inhalation risks were calculated for all exposure
scenarios based on the PPE and/or engineering controls described above.
For temephos, the same NOAEL was chosen for short, intermediate and
long term assessments. Because of the variability in usage, EPA has
calculated MOEs with both typical and maximum application rates and
acres treated. The resulting range of MOEs are presented in Table 3.

No adequate data are available; MOEs are assumed to be similar
to scenario (4) above.

(6) Applying emulsifiable concentrate using right-of way sprayer

40

0.0469

22

100

--

(7) Applying granulars using fixed wing aircraft

350

0.5

--

--

63

700

0.5

--

--

31

700

0.25

--

--

63

(8) Applying granulars using a helicopter

No adequate data are available for this scenario; MOEs are
assumed to be similar to scenario (7) above.

Flagger Exposure

(9) Flagging for liquid sprays

350

0.0469

280

330

14,000

700

0.0469

140

170

7,000

(10) Flagging for granulars

350

0.5

99

190

4,900

700

0.5

49

96

2,500

700

0.25

98

190

4,900

Mixer /Loader / Applicator Exposure

(11) M/L/A sprays with a backpack sprayer

5

0.0469

91

150

--

5

0.0313

136

225

--

(12) Loading / applying granulars with a power backpack blower

No exposure data are available to assess this use; MOEs are
assumed to be similar to scenario #13, below.

(13) Loading / applying granulars with a belly grinder

5

0.5

2.2

2.7

--

5

0.25

4.4

5.4

--

(14) Applying granulars by spoon (by hand used as a surrogate)

0.023

0.5

66

120

--

0.023

0.25

132

240

--

e. Post-Application Occupational and Residential
Risk

As mentioned earlier, the Agency believes that it is unlikely that
significant postapplication exposures to temephos would occur either
to workers or by-standers based on the relatively low application rate,
the limited use pattern, the short duration spent by the worker or bystanders
in the types of areas treated, and the low exposure activities performed
by the re-entry worker. Thus, no post-application assessments have been
conducted.

2. Aggregate Risk

An aggregate risk assessment looks at the combined risk from dietary
exposure from both food and drinking water sources, and residential
exposures. Because people are not expected to be exposed to temephos
from any of these sources, an aggregate assessment has not been conducted.

B. Environmental Risk Assessment

A summary of the Agency's environmental risk assessment is presented
below. For detailed discussions of all aspects of the environmental
risk assessment, see the Environmental Fate and Effects assessment,
entitled "Reregistration Eligibility Document for Temephos",
dated October 4, 1999, and "Response to Public Comments on Ecological
Risk Assessment for Temephos," dated October 5, 1999, which is
Attachment 1 to the "Response to Public Comments on the Preliminary
Risk Assessments for the Organophosphate Pesticide Temephos," both
are available in the public docket and on the Internet.

Major revisions have been made since the preliminary risk assessment
was completed. Both the registrant, Clarke Mosquito Control Company
Inc. and Lee County Florida Mosquito Control District submitted temephos-specific
literature studies and field studies to address the many data gaps that
had been identified in the preliminary assessment. While these studies,
for the most part, were not adequate to satisfy guideline requirements,
they contained much useful information that allowed EPA to conduct a
more thorough revised ecological assessment.

1. Environmental Fate and Transport

The presence of microorganisms in aquatic environments and exposure
to sunlight are likely to be the predominant means of transformation/dissipation
of temephos. In the absence of microorganisms or sunlight, temephos
does not dissipate significantly in water. The potential effect of sunlight
on temephos is decreased by the presence of dense vegetation which may
commonly shade temephos treated waters.

Temephos can bind strongly to soils and sediments and is unlikely to
volatilize from either under most conditions. However, temephos could
potentially volatilize slowly from shallow water. Transformation products
of temephos, such as temephos sulfoxide, temephos sulfone, temephos
sulfide and sulfone phenols do not bind to soil as strongly as temephos
and are, therefore, more likely to migrate to and remain dissolved in
the water.

Temephos, being a hydrophobic chemical and thus more likely to bind
to fatty substances, has the potential to bioconcentrate. Temephos bioaccumulated
in fish exposed to temephos for 28 days. However, more than 75% of the
temephos was eliminated after 14-days of non-exposure.

The major transformation products of temephos are temephos sulfoxide
and temephos sulfone. Temephos sulfide and sulfone phenols have also
been identified in water/sediments under anaerobic and aerobic conditions.
The only major degradate of temephos identified in irradiation-exposed
samples was temephos sulfoxide.

The low solubility of 0.030 mg/L and the relatively high Koc
of 16, 250 might suggest that some laboratory sediment toxicity testing
should be performed. However, measurements of residues in sediment from
field studies submitted by the registrant generally concluded that temephos
tends to rapidly adsorb to organic media and further degrade to low
or undetectable concentrations. The most recent field study, which monitored
temephos in sediments over a three year period, (1995-1997) did not
detect temephos in the sediment after 24 hours. As a result of these
field data, a sediment toxicity study will not be necessary at this
time.

2. Risk to Water Resources

Temephos is applied directly to non-potable, stagnant, saline, brackish
and polluted waters. Exposure to temephos and its degradation products
is limited to these aquatic environments, where mosquito breeding occurs.
These waters are unsuitable as a source of drinking water. Even if temephos
were applied to water used as a source of drinking water, e.g., reservoirs
and ox-bow lakes, dilution and residence time would reduce exposures
to temephos at the drinking water intake. Temephos degrades relatively
rapidly in natural water. Model concentrations indicate that there is
little effect of repeat applications on peak concentrations of temephos;
however, longer-term concentrations in woodland pools increase when
temephos treatments recur at intervals of 7 or 15 days. In estuarine
environments where tidal flushing occurs repeat applications are not
expected to result in accumulation of temephos.

Temephos is not likely to reach ground water that would be used for
drinking water due to its relatively short half-life in natural waters
and the lack of transport in typical temephos use areas--because temephos
is a larvicide, it is formulated to remain on the water's surface where
larvae are located. It was therefore determined that there was no need
to further evaluate temephos occurrence in ground water or surface water
used for drinking.

Several commenters noted that temephos is used in some countries to
treat drinking water. Since temephos is not used in potable water in
the United States and this use is not supported for reregistration,
the Agency has not conducted a drinking water risk assessment.

3. Risk to Aquatic Species

To estimate potential ecological risk EPA integrates the results of
exposure and ecotoxicity using the risk quotient method. Risk quotients
(RQs) are calculated by dividing exposure estimates by ecotoxicity values,
both acute and chronic, for various wildlife species. RQs are then compared
to levels of concern (LOCs). Generally, the higher the RQ, the greater
the potential risk. Risk characterization provides further information
on the likelihood of adverse effects occurring by considering the fate
of the chemical in the environment, communities and species potentially
at risk, their spatial and temporal distributions, and the nature of
the effects observed in studies.

Fish

Temephos is categorized as slightly to moderately toxic to freshwater
fish on an acute basis. No data are available to characterize toxicity
to marine fish species. The Risk Quotients derived from the current
freshwater fish acute toxicity studies exceed the levels of concern
for the emulsifiable concentrate formulation only for restricted use
and endangered species, the risk quotients for the granular formulation
do not exceed the levels of concern. EPA has no data on acute toxicity
of any marine fish species. Acute risk quotients for freshwater fish
based on a rainbow trout LC50 of 3490 ppb, (study performed with the
TGAI) and a granular application rate of 0.5 lbs/ai/A are given below.
Calculations assume aerial or ground applications to an intermittent
pond of 15 or 30 centimeter depth.

Acute risk quotients for freshwater fish based on a rainbow trout LC50
of 158 ppb, (study performed with a EC formulated product) and a maximum
application rate of 0.047 lbs/ai/A are given below. Calculations assume
aerial or ground applications to an intermittent pond of 15 or 30 centimeter
depth.

The Agency had some concern for chronic risk to fish because temephos
labels allow repeated applications to water. LC50 values
of less than 1 ppm have been demonstrated for both aquatic invertebrates
and fish. However, a number of field studies have been submitted which
show that even after ten applications of the granular Abate® 2G
formulation no chronic effects to fish were observed. Growth retarding
effects in fish were observed in one study after 4 applications of the
liquid Abate® 4E formulation, but because details of the studies
were not given, the Agency does not have a high level of confidence
in the results of this study. Review of the extensive field data that
were submitted during Phase 3 addresses the concern for chronic risk
to fish; no further data will be necessary at this time.

Aquatic Invertebrates

Temephos is "highly toxic" to "very highly toxic"
to freshwater and marine/estuarine aquatic invertebrates. The emulsifiable
concentrate appears to be much more toxic than the granular formulation
in laboratory studies, however this conclusion is based on a single
valid study with a 5% granular formulation. Acute risk quotients for
freshwater invertebrates based on a stonefly Pteronarcesspp.
LC50 of 10 ppb, (study performed with the TGAI) and a maximum granular
application rate of 0.5 lbs/ai/A are given below. Calculations assume
aerial or ground applications to an intermittent pond of 15 or 30 centimeter
depth.

Acute risk quotients for freshwater invertebrates based on a Daphnia
magna LC50 of 0.011 ppb, (study performed with a EC formulated
product) maximum application rate of 0.047 lbs/ai/A are given below.
Calculations assume aerial or ground applications to an intermittent
pond of 15 or 30 centimeter depth.

Some field data for freshwater invertebrates show that non-target aquatic
invertebrate populations tend to reestablish their original population
levels (i.e. numbers) within three weeks after application, however,
other field data show that recovery patterns (i.e. species diversity)
are altered. Additionally, as shown in the above table laboratory studies
show Daphnia magna to be extremely sensitive resulting in risk
quotients being exceeded by many orders of magnitude for the emulsifiable
concentrate.

Chronic risk to the estuarine environment was difficult to characterize
due to the lack of marine/estuarine invertebrate chronic data. The risk
quotients on the acute data based on the TGAI did not greatly exceed
the levels of concern. However, levels of concern are greatly exceeded
for the EC formulated product. Although no acceptable chronic studies
have been submitted for marine/estuarine invertebrates, a number of
field studies have been submitted which have demonstrated that adverse
effects to aquatic ecosystems are minimized when temephos is used at
the lower (0.0313 lbs/ai/A) application rate.

4. Risk to Birds and Mammals

Because Temephos is only applied directly to water, it is not expected
to have a direct impact upon terrestrial animals. No acute risk quotients
have been calculated, however, EPA has modeled the possibility of terrestrial
animals being exposed to temephos via drinking water using an avian
species (Mallard duck). Results of the modeling indicate that the amount
of temephos that the duck would be exposed to through normal water intake
is much less than the potentially lethal concentration, and thus not
of concern.

Additionally, due to the tendencies for temephos to bioconcentrate,
a piscivorous bird scenario was modeled to assess the risk to fish-eating
birds. This assessment was based on the comparison of the bioconcentration
factor (BCF) and resulting residues in fish viscera, to an avian subacute
dietary LC50. It was concluded that residue levels are expected
to be lower than the avian subacute dietary LC50. This assessment
indicates that only endangered species RQs may be exceeded in the 15
cm pond depth scenario.

There are no guideline data on the potential chronic effects of the
intake of food by waterfowl or upland game birds. However field data
that have been submitted for review indicate that there is very little,
if any, impact on birds. Therefore, EPA will not require a chronic bird
study at this time. In addition, since birds are not expected to be
affected by direct applications to water and no effects were noted in
the field data, EPA will not require acute testing on the formulated
product.

IV. Risk Management and Reregistration Decision

A. Determination of Reregistration Eligibility

Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after
submissions of relevant data concerning an active ingredient, whether
products containing the active ingredient are eligible for reregistration.
The Agency has previously identified and required the submission of
the generic (i.e., active ingredient specific) data necessary to support
reregistration of products containing temephosactive
ingredients.

The Agency has completed its assessment of the human health and ecological
risks associated with the use of pesticides containing the active ingredient
temephos of organophosphates as a class. Based on a review of these
data and public comments on the Agency's assessments for the active
ingredient temephos, EPA has sufficient information on the human health
and ecological effects of temephos to make a reregistration eligibility
decision. Because temephos has no dietary or residential exposure concerns,
it is not subject to further cumulative assessment for other organophosphates. This RED identifies risk reduction measures that
are necessary to allow the continued use of temephos. Appendix B. identifies
the generic data requirements that the Agency reviewed as part of its
determination, and lists the submitted studies that the Agency found
acceptable.

Based on its current evaluation of temephos alone, the Agency has determined
that temephos products, unless amended and used as specified in this
document, would present risks inconsistent with FIFRA. Accordingly,
should the registrant fail to implement any of the risk mitigation measures
identified in this document, the Agency may take regulatory action to
address the risk concerns from use of temephos. For temephos, if all
changes outlined in this document are incorporated into the labels,
then the risks associated with current use patterns will be mitigated.

1. Summary of Phase 5 Comments and Responses

When making its reregistration decision, the Agency took into account
all comments received during Phase 5 of the OP public participation
process. After the Stakeholder meeting in Orlando in October of 1999,
33 comments were received in EPA's public docket for temephos. Of these,
31 were from officials of mosquito abatement districts and other government
agencies, and of those 22 were from Florida, 5 from Illinois, 3 from
Louisiana and 1 from Mississippi. These generally supported the continued
use of temephos and attested to the benefits of its use. One comment
was received from a public interest group, Sarasota/Manatee Citizens
Rally Against Malathion (SCRAM). One comment was received from Wellmark
International, a registrant of methoprene products. These comments in
their entirety are available in the docket. A brief summary of the comments
and the Agency response is noted here.

Comment: Many stakeholders felt that EPA should place
greater weight on the benefits of temephos use.

Response: EPA acknowledges the public health benefits
of temephos use to control mosquito larvae and has considered these
benefits in its regulatory decision. See Section IV. C.3 below for a
complete discussion of the FQPA provisions dealing with public health
uses.

Comment: Several stakeholders were concerned about
the potential for heat stress with additional protective equipment,
since temephos is used primarily during the hottest time of the year.

Response: EPA is also concerned about heat stress and
has considered this issue carefully in development of the Worker Protection
Standard. In the case of temephos, double-layer clothing is needed for
mixing and loading emulsifiable concentrate, loading granulars for aerial
application, and for applications with a right-of way sprayer. In all
cases closed mixing, loading and closed cabs are also an option. Also,
route specific (dermal) toxicity data is necessary. Should these data
indicate lower risks than the current assessment, EPA will revisit the
PPE recommendations. See also Section IV. C.1 for a discussion of considerations
related to heat stress.

Comment: Several stakeholders commented that the requirement
on current labels to consult State Fish and Game Agencies before applying
temephos products to waters or wetlands was counter productive. In many
states, Fish and Game agencies have no regulatory oversight of mosquito
control programs and are confused by such calls. Further, mosquito control
agencies still must develop management plans with the relevant State
and Federal agencies (including approval of pesticides to be used) when
conducting operations on State and Federally owned lands.

Response: The language on current labels is obsolete
and must be deleted. See PR Notice 88-1. This language was initially
intended to address endangered species concerns. Registrants of temephos
have agreed to include EPA's endangered species web site address on
their product labels, so that users have access to all existing county
bulletins.

Comment:The SCRAM comment urged EPA to eliminate
the use of temephos for mosquito larviciding, citing its effects on
non-target organisms and the availability of safer alternatives.

Response: Some alternatives to temephos pose less risk
to humans than temephos. However, all available larvicides have some
impact on non-target aquatic organisms. Furthermore, there are certain
situations where available alternatives do not achieve adequate control.
See Section IV. C.3 below for a more complete discussion of alternatives.

Comment: Wellmark International took exception to EPA's
reference to temephos use in managing resistance to methoprene. They
noted that the only documented resistance to methoprene had been in
a strain of Aedes taeniorhynchus mosquitos in Lee County, Florida.
Attached to their comment were abstracts from a literature search documenting
resistance to temephos in the Caribbean, South America, Asia, Middle
East, Europe, and North America.

Response: EPA and HHS acknowledge that resistance to
temephos has developed in some parts of the world, due to its widespread
use to control the vectors of dengue and malaria, and also perhaps due
to its use at less than optimal rates. Nonetheless, it is the only OP
with any significant larvicide use in the US, and as such, is an important
tool for integrated control of mosquitos.

B. Regulatory Position

1. FQPA Assessment

No aggregate or cumulative assessments, as required by FQPA, have been
conducted for temephos. This chemical has no food uses, is not likely
to be found in drinking water, and is not used in or around homes or
areas that children frequent. All tolerances for temephos have been
revoked.

2. Endocrine Disruptor Effects

EPA is required under the FFDCA, as amended by FQPA, to develop a screening
program to determine whether certain substances (including all pesticide
active and other ingredients) "may have an effect in humans that
is similar to an effect produced by a naturally occurring estrogen,
or other such endocrine effects as the Administrator may designate."
Following the recommendations of its Endocrine Disruptor Screening and
Testing Advisory Committee (EDSTAC), EPA determined that there were
scientific bases for including, as part of the program, the androgen
and thyroid hormone systems, in addition to the estrogen hormone system.
EPA also adopted EDSTAC's recommendation that the Program include evaluations
of potential effects in wildlife. For pesticide chemicals, EPA will
use FIFRA and, to the extent that effects in wildlife may help determine
whether a substance may have an effect in humans, FFDCA authority to
require the wildlife evaluations. As the science develops and resources
allow, screening of additional hormone systems may be added to the Endocrine
Disruptor Screening Program (EDSP).

When the appropriate screening and/or testing protocols being considered
under the Agency's EDSP have been developed, temephos may be subjected
to additional screening and/or testing to better characterize effects
related to endocrine disruption.

3. Labels

Label amendments are needed for temephos products. Provided the following
risk mitigation measures are incorporated in their entirety into labels
for temephos-containing products, the Agency finds that all currently
registered uses of temephos except application by belly grinder, would
be eligible for reregistration. The regulatory rationale for each of
the mitigation measures outlined below is discussed immediately after
this list of mitigation measures. Specific label language is given in
Table 8: Summary of Labeling Changes for Temephos in Section V.

a. Occupational Risk Mitigation

To address risk to mosquito abatement workers who mix, load and apply
temephos products, the following measures will be necessary:

For mixing
and loading emulsifiable concentrate for aerial application and rights-of-way
sprayers labels will contain the following options:

-baseline work clothes, chemical resistant gloves, chemical resistant
apron + closed mixing and loading system (Note: A dry coupling device
for current containers would be adequate.)

Limit applications to public health officials, personnel of mosquito
abatement districts and similar government agencies, or personnel
under contract to these entities.

Limit use of the high application rates only to non-potable waters
high in organic matter content, areas demonstrated to have resistant
mosquitos, habitats having deep water or dense surface cover and where
monitoring has confirmed a lack of control at typical rates.

Provide EPA's web site address on labels for information on endangered
species.

Augment current environmental hazard statement to reflect the high
acute toxicity to non-target aquatic invertebrates, shrimp and crabs.

C. Regulatory Rationale

The following is a characterization of the risks and a summary of the
rationale for the mitigation measures outlined in the previous section.

1. Rationale for Occupational Risk Mitigation

Consistent with the PRN 2000-9, the registrants of temephos have agreed
to protective equipment and engineering controls to the extent feasible.
For all handler and applicator scenarios, MOEs are near or over 100
except: loading granulars for aerial application (MOEs range from 41-82,
depending on amount handled (acres treated) and application rate); and
applying granulars using fixed-wing aircraft and helicopter (MOEs range
from 31-63, depending on acres treated and application rate). EPA believes
that the risk represented by these ranges are not of concern given the
off-setting public health benefits of temephos, the protective assumptions
inherent in the Agency's assessment, and the fact that all available
protective measures are being implemented, along with the development
of key confirmatory data to reduce uncertainty associated with current
risk estimates.

Reliable usage data provided by the American Mosquito Control Association,
individual mosquito abatement districts, and other sources, indicate
that the high application rates and high acreage numbers represented
by the low end of the MOE range, are seldom used, and even less frequently
do these "worst case" conditions occur together. PHED aerial
exposure data used in the temephos assessments are based on small acreage
and extrapolated to larger areas. Moreover, available exposure data
are based on agricultural applications that may not be the most accurate
reflection of actual exposure for the mosquito larvicide applications.
There are no adequate data available to estimate exposure from helicopter
applications. Additional refinement of the toxicity endpoint(s) will
be possible with the route-specific dermal toxicity data which will
be required in this RED. Current toxicity data show only RBC ChE inhibition,
no brain inhibition or clinical signs. No incidents of worker exposure
or poisoning have been reported to EPA or other agencies that collect
incident data.

The Agency has no exposure data to evaluate the risk from loading and
applying granulars with a power backpack blower. Because of the high
application rate (equivalent to about 20 lbs/ai/A) and the type of application
equipment, EPA anticipates that exposure could be high. The registrant
has agreed to maximum PPE. Exposure data to characterize this use will
be required along with this RED.

The power backpack blower application to tire piles is a minor but
critical use. It represents <1% of all temephos use. The temephos
product used for this application is uniquely formulated for penetration
of large tire piles and residual action (30 days or more). It is more
effective and longer lasting than alternatives for this use.

Heat Stress

In the course of developing mitigation for temephos, the registrant
and other commenters raised the issue of heat stress to workers from
additional protective equipment, such as cloth coveralls and respirators.
This issue has been dealt with extensively in implementation of the
Worker Protection Standard. Numerous publications and information on
the recognition and management of heat stress can be found on EPA's
site at www.epa.gov/pesticides/safety/workers/.
The Agency is concerned about the potential for added heat stress, and
for nearly all temephos uses, has provided users with options to the
double layer of clothing. In general, the Agency supports the development
and use of closed mixing and loading equipment and enclosed application
equipment as noted in PRN 2000-9. In the case of temephos, emulsifiable
concentrate formulation products would be readily adaptable to inexpensive
coupling devices that would reduce exposure to handlers. Furthermore,
information provided by registrants and other stakeholders, indicates
that mixing and loading activities for mosquito control operations are
intermittent in nature and would not require long periods of continuous
use of PPE. Finally, it should be noted that the registrant must develop
route-specific dermal toxicity data. If these data indicate lower risk
to workers than currently estimated, PPE requirements may be revised.

2. Rationale for Environmental Risk Mitigation

All currently available mosquito larviciding techniques present some
risk to non-target aquatic species and the aquatic ecosystem. Although
temephos presents relatively low risk to birds and terrestrial species,
available information suggests that it is more toxic to aquatic invertebrates
than alternative larvicides. For that reason, label amendments are warranted
that limit the use of temephos to areas where less hazardous alternatives
would not be effective. These include limiting use sites, specifying
interval between applications, and limiting the use of the high application
rates. Based on information from stakeholders, these measures, to a
large extent represent current practice, but are not reflected on current
labels. Current risk estimates show acute risk quotients exceeded by
5-fold for stonefly and by many orders of magnitude for Daphnia
magna. These RQs were calculated with maximum application rates
and application intervals ranging from 7-90 days. Non-guideline field
studies demonstrate that adverse effects to aquatic ecosystems are minimized
when temephos is used at the lower application rate of 1 fl. oz. per
acre (0.0313lbs/ai/A).

EPA believes that the risk represented by these risk quotients are
not of concern given the off-setting public health benefits of temephos
use, the low volume of temephos use, the absence of wildlife exposure
incidents related to temephos, and the documented low frequency of use
at the high application rate.

3. Benefits of Temephos Use

The FQPA amendments to FIFRA require EPA to balance the risks of
a public health pesticide use against the risk to the public of the
diseases carried by the pests that these compounds control. The statute
further requires, among other things, that EPA consult with the Secretary
of Health and Human Services (HHS) prior to taking final action to suspend
or cancel a public health pesticide's registration. Although EPA is
not proposing to cancel or suspend any temephos uses, the Agency has
sought comments from HHS on the benefits of temephos use in controlling
public health pests.

In a letter dated April 13, 1999, HHS notes that temephos is an inexpensive,
valuable tool for managing many mosquito species, including container-breeders
like Aedes albopictus and Aedes aegypti. The former
species has been implicated as a carrier of Eastern equine encephalitis,
a highly lethal disease in humans and horses in the United States.

Pest species and disease incidences vary from state to state and
year to year. Targeted species include potential and actual vectors
of St. Louis encephalitis, Venezuelan equine encephalitis, Eastern equine
encephalitis, LaCrosse encephalitis, Western equine encephalitis, malaria,
yellow fever, West Nile virus, and dengue. Species that are actual and
potential vectors of the above diseases in widespread areas of the US
and that are targeted by temephos include Aedes aegypti, A. albopictus,
A. triseriatus, A. sollicitans, A. taeniorhynchus, Anopheles quadrimaculatus,
and Culex pipiens. A significant number of cases of St.
Louis encephalitis and Eastern equine encephalitis surface in the US
annually. These diseases are significant because of their high mortality
rate among humans. West Nile virus is a new disease with several fatal
human cases in 1999 and 2000 which seems to be spreading southward from
the northeastern US. Incidences of malaria and dengue have been increasing
in Central and South America. Dengue is regularly reported from Puerto
Rico and other Caribbean islands and indigenous cases have recently
been reported from Texas. While none of the cases of malaria reported
in the US recently were from indigenous sources, there is a threat that
local mosquitoes will become infected and begin transmitting it. Because
malaria microbes have recently developed resistance to several antimalarial
drugs, the hazards of malaria once it is in the human population have
increased. Temephos has been successfully used to reduce populations
of the vectors of the above diseases.

Alternatives to temephos include methoprene, Bacillus thuringiensis
israelensis Bti, Bacillus sphaericus (Bs), Lagenidium
giganteum (Laginex), pyrethrins, malathion, oil, monomolecular
films, and diflubenzuron. Temephos is generally used in rotation with
one or more of the alternatives to prevent the development of resistance
to any one product. Temephos is critical for US larviciding operations
because it is effective in polluted water, has a long residual, is available
in several use-specific formulations, has a different mode of action
than alternatives, may be used on any size (growth stage) larvae, and
has contact toxicity against all target species.

Abate® has emulsifiable concentrate and granular formulations that
are tailored to specific uses. The emulsifiable concentrate is effectively
applied aerially mainly by helicopter to open tidal water areas in Florida
inaccessible by roads. The granular is available as a heavy sand granule
with rapid release, a slow-release composite granule, and a corncob
slow-release granule. The sand granular form is effective where dense
canopies overhanging flood water must be penetrated. Composite granules
or pellets are amenable to power backpack sprayers or horn seeders used
in areas where trucks can not go and they are also applied by helicopter.
The corncob granule is specially formulated to penetrate tire piles
many of which are accessible only on foot with backpack blowers.

Abate® is the third most widely used larvicide after methoprene
and Bti. Methoprene is a growth regulator with the limitations of being
effective only on larvae at a certain growth stage, some resistance
problems, and having some formulation problems in the past. Bti has
the limitation that it must be ingested by small larvae and is not effective
in polluted water. Laginex is a live organism with a short shelf life
and unreliable efficacy. Pyrethrins are not used much because they have
a short residual and are very costly. Diflubenzuron has little use because
it is expensive, must be used only on small larvae, and lacks specificity.
Oils and monomolecular films are useful for pupiciding but leave an
undesirable sheen on water. Malathion is not used for larviciding, primarily
because of its widespread use as an adulticide. The only product specifically
designed for application to tire piles is Abate® 5% Tire
Treatment.

Larviciding is a part of mosquito integrated pest management programs
that include monitoring of mosquito larvae and adults and mosquito-borne
diseases, source reduction, habitat modification, use of biocontrol
agents such as mosquitofish, public education, adulticiding and pupiciding,
and rotation of pesticides. In general, larviciding is the choice for
control if source reduction, habitat modification, and biocontrol are
insufficient for control. Adulticiding is usually the last choice for
control. Control of the immature stages of the mosquito before adults
have a chance to emerge and disperse (or become infected with a pathogen)
is more effective and economical than widespread application of adulticides,
although complete control is seldom achieved with larviciding alone.

Although resistance to temephos has been demonstrated in some areas
of the world, it is the only remaining organophosphate larvicide with
any appreciable use in the United States. As such, it is an important
tool in managing resistance to the few alternatives available. HHS noted
that alteration in the registration status or availability of temephos
in the United States would likely have a major negative impact on the
ability to control dengue and yellow fever throughout the world. For
a complete discussion of benefits see, "BEAD Analysis of Public
Health Benefits of Temephos for Mosquito Control Use" dated October
4, 2000 which is available in the docket and on the Internet.

D. Other Labeling

In order to remain eligible for reregistration, other user and safety
information needs to be placed on the labeling of all end-use products
containing temephos. For the specific labeling statements, refer to
Section V. of this document.

1. Endangered Species Statement

The Agency has developed the Endangered Species Protection Program
to identify pesticides whose use may cause adverse impacts on endangered
and threatened species and to implement mitigation measures that will
eliminate the adverse impacts. At present, the program is being implemented
on an interim basis as described in a Federal Registry notice (54 FR
27984-28008, July 3, 1989), and providing information to pesticide users
to help them protect these species on a voluntary basis. As currently
planned, but subject to change as the final program in developed, the
final program will call for label modifications referring to limitations
on pesticide uses, typically as depicted in county-specific bulletins
or by other site-specific mechanisms as specified by state partners.
The final program, which will be altered from the interim program, will
be described in a future Federal Register notice. The Agency
is not requiring label modifications at this time through the RED. The
registrants of temephos have voluntarily agreed to put EPA's endangered
species web site address on product labels for informational purposes
only. Any requirements for product use modification will occur in the
future under the Endangered Species Protection Program.

2. Spray Drift Management

The Agency has been working with the Spray Drift Task Force, EPA Regional
Offices and State Lead Agencies for pesticide regulation and other parties
to develop the best spray drift management practices. The Agency is
proposing interim mitigation measures for aerial applications that should
be placed on product labels/labeling as specified in Section V. of this
document. The Agency has completed its evaluation of the new data base
submitted by the Spray Drift Task Force, a membership of US pesticide
registrants, and is developing a policy on how to appropriately apply
the data and the AgDRIFT computer model to its risk assessments for
pesticides applied by air. After the policy is in place, the Agency
may impose further refinements in spray drift management practices to
reduce off-target drift and risks associated with aerial as well as
other application types where appropriate. In the interim, labels should
be amended to include the following spray drift related language.

For products that are applied outdoors in liquid sprays (except mosquito
adulticides), regardless of application method, the following must be
added to the labels:

"Do not allow this product to drift."

For outdoor liquid or granular products that are applied aerially,
further label language is necessary for spray drift management. Specific
label language is outlined in Table 8. of this document.

V. What Registrants Need To Do

In order to be eligible for reregistration, registrants need to implement
the risk mitigation measures outlined in Section IV. and V., which include,
among other things, submission of the following:

(5) If applicable, a completed form certifying compliance with cost
share offer requirements (EPA Form 8570-32); and

The product-specific data responding to the PDCI.

Please contact Frank Rubis, at (703) 308-8184 with questions regarding
product reregistration and/or the PDCI. All materials submitted in response
to the PDCI should be addressed:

By US mail:

Document Processing Desk (PDCI/PRB)

Frank Rubis-CRM

US EPA (7508C)

1200 Pennsylvania Ave., NW

Washington, DC 20460

By express or courier service only:

Document Processing Desk (PDCI/PRB)

Frank Rubis-CRM

Office of Pesticide Programs (7508C)

Room 266A, Crystal Mall 2

1921 Jefferson Davis Highway

Arlington, VA 22202

A. Manufacturing Use Products

1. Additional Generic Data Requirements

The generic data base supporting the reregistration of temephos
has been reviewed and determined to be adequate to support the reregistration
eligibility of the mosquito larvicide use. The following confirmatory
data are necessary:

Ecological:

Old Guideline Number

New Guideline Number

Study Title

72-3 (a)

850.1075

Estuarine/Marine Toxicity - Fish, TEP EC

Human Health:

Old Guideline Number

New Guideline Number

Study Title

81-7

870.6100

Acute Delayed Neurotoxicity - Hen

82-2

870.3200

21-Day Dermal - Rat (1) (with
blood cholinesterase measurements at earlier time points within
the first 7 days and at 14 days)

EPA has worked closely with the registrant of temephos and other
stakeholders to reassess the data requirements for this chemical in
light of its low volume and minor use. Because of the many good quality,
but non-guideline, ecological field monitoring studies available, EPA
has waived many guideline requirements. The remaining estuarine fish
acute toxicity study is necessary because there is likely exposure to
estuarine species, and these basic toxicity data are not currently available
from literature sources. Life cycle data on daphnia magna and shrimp
are not being required at this time. The registrant has agreed to precautionary
labeling related to the toxicity of temephos to aquatic species.

One study, the 21-day dermal toxicity in the rat with interim ChE measurements,
would address three guidelines-"Neurotoxicity Screening Battery-Acute"
(870.6200/81-8), "21-Day Dermal" (82-2), and "90-Day
Neurotoxicity" (82-5 (b)). Based on available data, we believe
that the onset of effects with temephos is relatively early, and that
response remains constant with longer exposures. The interim measurements
in the dermal toxicity study will enable EPA to confirm the dose-response
relationship and refine the hazard assessment with route-specific data.
A developmental toxicity study in a second species may also be necessary
for non-food chemicals if significant exposure is expected.

A Data Call-In Notice (DCI) was sent to registrants of organophosphate
pesticides currently registered under FIFRA (August 6, 1999 64FR42945-42947
and August 18, 1999 64FR44922-44923). DCI requirements included acute,
subchronic, and developmental neurotoxicity studies. EPA has waived
the developmental neurotoxicity study for temephos based on the low
volume of use, the lack of food uses and the low potential for any other
exposure to children. Requirements for acute, and subchronic neurotoxicity
studies can be addressed by the 21-day dermal toxicity study as noted
above.

The only exposure data necessary at this time is for the power backpack
blower scenario, because this method appears to be unique to temephos.
Additional exposure data will likely be necessary for temephos to better
characterize risk to workers and by-standers. Because the need for these
data applies to all chemicals used in mosquito control, EPA is currently
evaluating the most efficient and cost-effective approach for generating
this information.

2. Labeling for Manufacturing Use Products

To remain in compliance with FIFRA, manufacturing use product (MUP)
labeling should be revised to comply with all current EPA regulations,
PR Notices and applicable policies.

The MP labeling should bear the labeling contained in Table 8. at the
end of this section.

B. End-Use Products

1. Additional Product-Specific Data Requirements

Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed
product-specific data regarding the pesticide after a determination
of eligibility has been made. Registrants must review previous data
submissions to ensure that they meet current EPA acceptance criteria
and if not, commit to conduct new studies. If a registrant believes
that previously submitted data meet current testing standards, then
the study MRID numbers should be cited according to the instructions
in the Requirement Status and Registrants Response Form provided for
each product.

Labeling changes are necessary to implement the mitigation measures
outlined in Section IV. Specific language to incorporate these changes
is specified in the Table 8. at the end of this section.

C. Existing Stocks

Registrants may generally distribute and sell products bearing old
labels/labeling for 12 months from the date of the issuance of this
Reregistration Eligibility Decision document. Persons other than the
registrant may generally distribute or sell such products for 24 months
from the date of the issuance of this RED. However, existing stocks
time frames will be established case-by-case, depending on the number
of products involved, the number of label changes, and other factors.
Refer to "Existing Stocks of Pesticide Products; Statement of Policy";
Federal Register, Volume 56, No. 123, June 26, 1991.

The Agency has determined that the registrant may distribute and sell
temephos products bearing old labels/labeling for 12 months from the
date of issuance of this RED. Persons other than the registrant may
distribute or sell temephos products for 24 months from the date of
the issuance of this RED. Registrants and persons other than the registrant
remain obligated to meet pre-existing label requirements applicable
to products they sell or distribute.

D. Table 8: Summary of Labeling Changes for Temephos

In order to be eligible for reregistration, registrants will need to
amend all product labels to incorporate the risk mitigation measures
outlined in Section IV. The following table describes how language on
the labels should be amended.

Table 8: Summary of Labeling Changes for Temephos

Description

Amended Labeling

Placement on Label

Manufacturing Use Products

Required on all Manufacturing Use Products

"Only for formulation into an insecticide for the following
use: mosquito, gnat, midge, punkie, and blackfly larvicide."

Directions for Use

One of these statements may be added to a label to allow reformulation
of the product for a specific use or all additional uses supported
by a formulator or user group

"This product may be used to formulate products for specific
use(s) not listed on the MP label if the formulator, user group,
or grower has complied with US EPA submission requirements regarding
support of such use(s)."

"This product may be used to formulate products for any
additional use(s) not listed on the MP label if the formulator,
user group, or grower has complied with US EPA submission requirements
regarding support of such use(s)."

"This product is toxic to aquatic organisms such as stone
flies, water fleas, and shrimp. Non-target aquatic organisms in
waters treated with this product may be killed. Some populations
reestablish rapidly, but diversity may be affected. Avoid use
of maximum application rate in ecologically sensitive areas. Do
not contaminate water by cleaning of equipment or disposing of
wastes."

"In addition loaders supporting aerial applications and
loaders/applicators using a backpack power blower on tire pile
sites must wear:

A NIOSH-approved dust mist filtering respirator with NSHA/NIOSH
approval number prefix TC-21C* or a NIOSH-approved
respirator with any N, R, P, or HE filter"

Note: The registrant must drop the N filter from the respirator
statement if the pesticide product contains or is used with oil.

Precautionary Statements: Following PPE and User Safety Requirements

User Safety Requirements

"Follow manufacturer's instructions for cleaning/maintaining
PPE. If no such instructions for washables exist, use detergent
and hot water. Keep and wash PPE separately from other laundry.
Discard clothing and other absorbent materials that have been
drenched or heavily contaminated with this product's concentrate.
Do not reuse them."

Precautionary Statements: Following the PPE requirements

Engineering Controls for emulsifiable concentrate/liquid products

"Engineering Controls"

"When mixers and loaders use a closed system designed by
the manufacturer to enclose the pesticide to prevent it from contacting
handlers or other people AND the system is functioning
properly and is used and maintained in accordance with the manufacturer's
written operating instructions, the handlers:

-- may wear long-sleeve shirt and long pants, shoes plus socks,
chemical-resistant gloves and chemical-resistant apron, instead
of the PPE necessary for mixers and loaders in the PPE section
of this labeling,

-- must wear protective eye wear if the system operates under
pressure, and

-- must have immediately available for use in an emergency, such
as a broken package, spill, or equipment breakdown, all PPE necessary
for mixers and loaders in the PPE section of this labeling."

"Pilots must use an enclosed cockpit and must wear chemical
resistant gloves when entering or leaving an aircraft contaminated
by pesticide residues. Used gloves must be stored in a closed
chemical resistant container, such as a plastic bag, to prevent
contamination of the inside of the cockpit."

"When ground applicators and flaggers use an enclosed cab
that has a nonporous barrier that totally surrounds the occupants
and prevents contact with pesticides outside the cab, they:

-- may wear a long-sleeve shirt and long pants, shoes, and socks,
instead of the PPE necessary for such applicators and flaggers
in the PPE section of this labeling, and

-- must be provided and must have immediately available for use
in an emergency the handler PPE specified for applicators or flaggers
when they must exit the cab in the treated area and,

-- must take off any PPE that was worn in the treated area before
reentering the cab, and

-- must store all such PPE in a chemical-resistant container,
such as a plastic bag, to prevent contamination of the inside
of the cab."

Precautionary Statements: Following PPE and User Safety Requirements

Engineering Controls for Granular Products

"Engineering Controls"

"Pilots must use an enclosed cockpit and must wear chemical
resistant gloves when entering or leaving an aircraft contaminated
by pesticide residues. Used gloves must be stored in a closed
chemical resistant container, such as a plastic bag, to prevent
contamination of the inside of the cockpit."

Precautionary Statements: Following PPE and User Safety Requirements

User Safety Recommendations

"User Safety Recommendations"

"Users should wash hands before eating, drinking, chewing
gum, using tobacco, or using the toilet."

"Users should remove PPE immediately after handling this
product. Wash the outside of gloves before removing. As soon as
possible, wash thoroughly and change into clean clothing."

Precautionary Statements: Following Engineering Controls

(Must be placed in a box.)

Environmental Hazards

"This product is toxic to aquatic organisms such as stone
flies, water fleas, and shrimp. Non-target aquatic organisms in
waters treated with this product may be killed. Some populations
reestablish rapidly, but diversity may be affected. Avoid use
of maximum application rate in ecologically sensitive areas. Do
not contaminate water by cleaning of equipment or disposing of
wastes."

"This product may be applied only by public health officials,
personnel of mosquito abatement districts and other similar government
agencies or personnel under contract to these entities."

"Maximum application rates may be used only in waters
high in organic matter content, mosquito habitats having deep
water or dense surface cover, and where monitoring has confirmed
a lack of control at typical rates."

"This product may not be reapplied within 7 days of the
date of the initial application unless monitoring indicates that
larval populations have reestablished, or weather conditions have
rendered initial treatments ineffective."

“This product may be applied as a spot treatment to non-potable
water, lakes, and ponds for control of midge larvae when monitoring
indicates threshold levels have been exceeded."

Place in the Direction for Use directly above the Agricultural
Use Box

Spray Drift Restrictions

for Outdoor Products Applied as a Liquid

"Do not allow this product to drift."

Directions for Use in General Precautions and Restrictions

Spray Drift language for products applied aerially

"Aerial Spray Drift Management"

"Avoiding spray drift at the application site is the responsibility
of the applicator. The interaction of many equipment-and-weather-related
factors determine the potential for spray drift. The applicator
and the grower are responsible for considering all these factors
when making decisions."

Directions for Use

Drift Language for products applied aerially

"The following drift management requirements must be followed
to avoid off-target drift movement from aerial applications. These
requirements do not apply to applications using dry formulations.

1. The distance of the outer most nozzles on the boom must
not exceed 3/4 the length of the wingspan or rotor.

2. Nozzles must always point backward parallel with the air
stream and never be pointed downwards more than 45 degrees.

Where states have more stringent regulations, they should be
observed.

The applicator should be familiar with and take into account
the information covered in the Aerial Drift Reduction Advisory
Information."

Directions for Use

Drift Language for products applied aerially

"Aerial Drift Reduction Advisory"

"This section is advisory in nature and does not supercede
the mandatory label requirements."

"INFORMATION ON DROPLET SIZE"

"The most effective way to reduce drift potential is to
apply large droplets. The best drift management strategy is to
apply the largest droplets that provide sufficient coverage and
control. Applying larger droplets reduces drift potential, but
will not prevent drift if applications are made improperly, or
under unfavorable environmental conditions (see Wind, Temperature,
and Humidity, and Temperature Inversions)."

"Number of nozzles - Use the minimum number of nozzles
that provide uniform coverage."

"Nozzle Orientation - Orienting nozzles so that the spray
is released parallel to the airstream produces larger droplets
than other orientations and is the recommended practice. Significant
deflection from horizontal will reduce droplet size and increase
drift potential."

"Nozzle Type - Use a nozzle type that is designed for the
intended application. With most nozzle types, narrower spray angles
produce larger droplets. Consider using low-drift nozzles. Solid
stream nozzles oriented straight back produce the largest droplets
and the lowest drift."

Directions for Use

Drift Language for products applied aerially

"BOOM LENGTH"

"For some use patterns, reducing the effective boom length
to less than 3/4 of the wingspan or rotor length may further reduce
drift without reducing swath width."

Directions for Use

Drift Language for products applied aerially

"APPLICATION HEIGHT"

"Applications should not be made at a height greater than
10 feet above the top of the largest plants unless a greater height
is necessary for aircraft safety. Making applications at the lowest
height that is safe reduces exposure of droplets to evaporation
and wind."

Directions for Use

Drift Language for products applied aerially

"SWATH ADJUSTMENT"

"When applications are made with a crosswind, the swath
will be displaced downward. Therefore, on the up and downwind
edges of the field, the applicator must compensate for this displacement
by adjusting the path of the aircraft upwind. Swath adjustment
distance should increase, with increasing drift potential (higher
wind, smaller drops, etc.)."

Directions for Use

Drift Language for products applied aerially

"WIND"

"Drift potential is lowest between wind speeds of 2-10 mph.
However, many factors, including droplet size and equipment type
determine drift potential at any given speed. Application should
be avoided below 2 mph due to variable wind direction and high
inversion potential. NOTE: Local terrain can influence wind patterns.
Every applicator should be familiar with local wind patterns and
how they affect spray drift."

Directions for Use

Drift Language for products applied aerially

"TEMPERATURE AND HUMIDITY"

"When making applications in low relative humidity, set
up equipment to produce larger droplets to compensate for evaporation.
Droplet evaporation is most severe when conditions are both hot
and dry."

Directions for Use

Drift Language for products applied aerially

"TEMPERATURE INVERSIONS"

"Applications should not occur during a temperature inversion
because drift potential is high. Temperature inversions restrict
vertical air mixing, which causes small suspended droplets to
remain in a concentrated cloud. This cloud can move in unpredictable
directions due to the light variable winds common during inversions.
Temperature inversions are characterized by increasing temperatures
with altitude and are common on nights with limited cloud cover
and light to no wind. They begin to form as the sun sets and often
continue into the morning. Their presence can be indicated by
ground fog; however, if fog is not present, inversions can also
be identified by the movement of smoke from a ground source or
an aircraft smoke generator. Smoke that layers and moves laterally
in a concentrated cloud (under low wind conditions) indicates
an inversion, while smoke that moves upward and rapidly dissipates
indicates good vertical air mixing."

Directions for Use

Drift Language for products applied aerially

"SENSITIVE AREAS"

"The pesticide should only be applied when the potential
for drift to adjacent sensitive areas (e.g. residential areas,
non-target bodies of water, known habitat for threatened or endangered
species, non-target crops) is minimal (e.g. when wind is blowing
away from the sensitive areas)."

Directions for Use

Instructions in the Labeling section appearing in quotations
represent the exact language that should appear on the label.

Instructions in the Labeling section not in quotes represents
actions that the registrant should take to amend their labels or product
registrations.

1 The 21-day dermal toxicity study in the rat with
interim ChE measurements would be used to address three guidelines--"Neurotoxicity
Screening Battery-Acute" (870.6200 / 81-8), "21-Day Dermal"
(82-2), and "90-Day Neurotoxicity" (82-5 (b)).

2 The developmental (teratogenicity) study in a
second species may be required depending on the outcome of the 21-day
dermal study. Because temephos has no food uses, this study may be waived
if data demonstrate low potential for exposure.

3 PPE that is established on the basis of Acute
Toxicity of the end-use product must be compared to the active ingredient
PPE in this document. The more protective PPE must be placed in the
product labeling. For guidance on which PPE is considered more protective,
see PR Notice 93-7.